Air-refrigerating machine



1.460.677 l. LUNDGAARD AIR REFRIGERATING MACHINE Filed May 22. 1922 3SheetsfSheet l July 3, 1923.

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IN1/MOR Sheets-Sheet 2 i. LUNDGAARD AIR REFRIGERATING MACHINE Filed May22. 1922 AM ...HHH 1 `Fully 3, 1923'.

Jul'y "3, 1.923.

Filed May 22,

1922 3 Sheets-Sheet 5 IHIHIW duly 3,. i923,

intornfl'f LUNDGABD, OF HARTFORD, CONNECTICUT, SSIGNOR TO THE AUTOMATICBE- iS'R-EGERATJLNG COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OFNEW IBI-REFRGERTING MACHTNEL .application led Eay 22, 1922. Serial No.562,907.

v o @ZZ whom may cow/cam:

e it known that l, lvAR LUNDGAARD, a

citizen of the United States, and a resident "the air is expanded.Between these two chambers the .air is passed through a heat exchangerfor transferring heat from the compressed air to a body of coolingfluid, a regenerator for maintaining a difference of i temperaturebetween the air entering it and the air leaving it and a heat exchangerfor transferring heat from a fluid to be cooled to the expanded air` Tnmy Patent No. LFE-0,862 l have described a machine of this as the volumeof the air spaces in the heat er1-changers and regenerator is constantand as this volume is interposed between the compression and expansionchambers, it comprises what might be considered a clearance volume andit is obvious that to obtain any great amount of refrigeration thisvolurn-e must be small as compared to the piston displacement. Further alarge area mnst be presented to the air to transfer the heat to or fromit. y

Since the function of the regenerator is to bring the mediating air to atemperature as nearly as possible equal to that in the chamber it isentering, whether it be the reiatively hot compression chamber or. rela-11vely cold expansion chamber, it is necesary that it have capacitytoabsorb a given mount of heat during part of each cycle to given u atanother part of the cycle. i order t at the outputof refrigeration behigh, the regenerator must be constructed to prevent, as far as ispossible, the ccnduction of heat from its hot end to its cold end. 7Theobject of my present invention is to produce a regenerator that willcontain a' small volume of air, that' will present a large surface tothe air, that will be easy' and 1 v cheap to manufacture, that will havesuffi;I

.sections extendacross the path of low of cient heat capacity tomaintain its hot end and its cold end at the proper relativetemperatures, that will conduct the minimum amount of heat from its hotend to its cold end, and that will offer low resistance to the passageof air.

I accomplish this object by constructing my regenerator in the form of achamber, the walls of which are composed of heat insulating material,and providing in the chamber a plurality of sections of material havingthe required heat capacity, and eX* tended surface, and a multiplicityof narrow spaces for the passage of air. -These the mediating fluid andare separated from each -other so as not to be in heat-conductiverelation. Each section may, for example, consist of a plurality of turnsof thin metallic ribbons closely spaced with respect to each other andmounted so that their edges are presented in the direction of ow ofthemediating fluid.

n order that my invention may be clearly understood, it will bedescribed in connection with the accompanying drawings, and the novelfeatures will be pointed out inthe annexed claims. In said dravvinAFigure 1 is a vertical, longitudlnal section of my airJ refrigeratingmachine, of` which regenerators according to this invention form a part.

Figure 2 is a vertical, transverse section on an venlarged scale of oneof the regenerators shown in Figure 1.

Figure 3 is a bottom generator of Figure 2.

Figure 4 is a vertical, transverse section of another embodiment of myinvention.

Figure 5 is a bottom plan view of the regenerator of Figure 4 showing inpart the plan view of the remetallic strips forming the heat storageelements. Referring to Figure 1, the operation of the machine may be asfollows for one cycle of operations, which corresponds to one revolutionof the crank-shaft. The move` ments of the pistons are controlled by themechanism in the crank-case.

The air is compressed in the chamberbetween compression piston 1 andshifter pis-4 ton 2 by upward movement yof piston 1. It is thentransferred at the higher pressure through annular port 3, thespacesbetween leaves 4: of heat exchanger 5, the regenerator no theirupper ends heat i temperature at all Y between turns being 6 and thespaces between leaves 7 .ot heat exchanger 8 to the chamber aboveshifter piston 2. lt is then expanded in the chamber above piston 2 bydownward movement of both piston l and piston 2. Finally it istransferred back again at the lower pressure to the chamber betweenpiston l and piston f2 through heat exchanger 8, regenerator 6 and heatexchanger 5. In this way, heat is discharged from the system by heat eX-changer 5 and heat may be abstracted from any desired fluid by heatexchanger 8. A difference of temperature is established between the twoheat exchangers and consequently between the upper and lower ends ofregenerator 6.

The machine illustrated in Figure l has two cylinders and it will beunderstood that both cylinders are similarly constructed.

Regenerator' 6 compri-ses an inner cylindrical wall 9 of heat-insulatingmaterial, such as bakelite and an outer cylindrical wall 10 also ofheat-insulating material. An annular space is formed between the twowalls. falls 9 and l() rest at their lower ends on the heat exchanger 5and support at exchanger 8. Wall 9 serves also as a portion of thecylinder wall inside of which piston 2 reciprocates. lt is thus seenthat the regenerator acts to insulate the hot end of the machine fromthe cold end while at the same time acting as a regenerator for themediating fluid.

ln Figures 2 and 3, one embodiment of my invention is shown asconsisting of a plurality of thin metal ribbons ll, wound spirally onwall 9, each turn being immediately over another but separated therefromby narrow spacers 12, of insulating material, such as paper. Spacers l2are arranged about the circumference at intervals, sutilciently close tokeep the strips in position, and extend the full length of theregenerator. Each of the metallic ribbons 1l comprises a coil of severalwraps around cylinder and each coil is separated, in the direction offlow of the mediating air, from the adjacent coils so to beheat-insulated therefrom, As any one coil is at approximately the samepoints, it is important to subdivide the length of the regenerator intoas many coils and insulating spaces as will produce a relatively smoothtemperature gradient between the two ends. ln regenerators I haveconstructed, which have given excellent results, there have beennineteen coils each having thirty turns ot brass ribbcn one-eighth of aninch wide by twothousandths of an inch thick` the spacers paperone-sixteenth of an inch wide by six-t ousandths fil :in inch thick. andthe length-wise separation of the coils being eight-thousandths of aninch.

The outside diameter ot the coils of strips 1l is Such that outer.cylinder l0 will :ur-tedere' just slip over them. As the mediating airpasses back and forth through the narrow spaces between turns it readilygives up or absorbs heat from the strips, while at the same time thereis a small volume of air contained in the regenerator and a minimum oflength-wise conduction or heat.

ln Figures l and 5, l illustrate another embodiment of my invention. Thethin metal strips 1l are wound spirally about the cylinder 9 and eachturn is spaced Yfrom the previous turn by corrugated metallic strips 18,the corrugations of which extend in the direction of iow of themediating air. Therefore. each coil consists ot a number of alternatelayers of flat metal and corrugated metal strips wound together oncylinder 9. Each coil is separated Jfrom the neat by an air space sothat they will be in heat-insulating relation to each other. The numberof coils and their spacing is determined by the heat capacity requiredand the consideration orI length-wise heat conduction between the twoends of the regenerator.

Broadly my invention comprises a regenerator havin a number of sections,each consisting cig a plurality of spaced metal leaves presenting anextended surface to the mediating air and disposed within a body ofheat-insulating material in the path of the mediating air; each sectionbeing heatinsulated from the adjacent sections. lt is apparent thatnumerous forms of construction may be employed without departing fromthe scope of the invention as disclosed in connection with theembodiments illustrated.

l. closed cycle refrigerating system operating with gaseous mediatingfluid, comprising in combination a plurality ot heat absorbing anddelivering units, arran ed successively in the path of the mediating gasand in non-conductive relation to each other, means for insulating saidunits from outside environment, and means for causing the mediating gasto move past said units in succession.y

2. In a rerigerating machine,` a regenerator comprising a body ofheat-insulating material, a plurality of sections having capacity forabsorbing and giving up heat, arranged one after another within saidbody of heat-insulating material and forming aportion ot the path ot7the mediating gas, each of said sections being heatinsulated from theadjacent section.

3. ln a refrigerating machine, a regenerator comprising inner and outercircular walls of heat-insulating material having an annular spacebetween them to form a portion ot' the path of the mediating gas, aplurality of sections having capacity for absorbing and giving up heat,arranged within the annular space one after another but lili@ iis"heat-insulated from each other, said sections each presenting a largesurface to the medi- *ating gas and having a plurality of narrow cularwalls of heat-insulating material. having an annular space between themto form a portion of the path of the mediating air, and a plurality ofspirally wound meta'llic ribbons in said annular space having theirlayers spaced -from each other to form air spaces between layers, saidmetallic ribbons being heat-insulated from each other.v

5. In an air refrigerating machine, a regenerator comprising a chamberhaving walls of heat-insulating material and forming a portion of thepath of the mediating air, and a plurality of sections each consistingof metallic ribbons in closely spaced relation to each other andarranged in the path of the mediating air to subdivide the air flow intoa plurality of substantially equal small parts, said sections beingseparated so as to maintain them in heat-insulated relation to eachother.

6. An air refrigerating machine comprising\a compression piston and ashifter piston, inner and outer concentric circular walls ofheat-insulating material, the inner Wall forming a portion of the Wallof the cylinder in which said pistons reciprocate,

and the annular space between said two walls forming a portion of thepath of the mediating air, and a plurality of heat absorbing anddelivering units disposed in heat-insulated relation to each otherwithin the said annular space.

7. An air refrigerating machine comprising a compression piston and ashifter piston, inner vand outer concentric circular walls ofheat-insulating material, the Ainner wall forming a portion of the wallof the cylinder in which said pistons reciprocate, and the annular spacebetween said two walls forming a portion of the path of the mediatingair, and a pluralityA of coils of metallicribbons spirally Wound on saidinner wall in spaced relation to each-other, the layers of eachl of saidcoils being` spaced from each other by ay plurality of circumferentiallyspaced strips of heat-insulating the material extending along elementsof cylinder.

WAR LUNDGAARD.

